Prior art moving walks or escalators typically include a support truss and a plurality of interconnected steps or flat links that travel in a loop within the truss to provide a continuous movement along a specified path. When the escalator or moving walk assembly is appropriately mounted between the floors of a building, relative motion exists between the moving steps and the stationary structure of the conveyor system. If the escalator or moving walk assembly is rigidly mounted between the adjacent floors of a building, or between two separate buildings or structures, and no provision is made for relative movement between the escalator or moving walk assembly and the building structure, failures can occur during earthquakes or seismic events.
For this reason various states, including California, have adopted specific seismic requirements for escalators and moving walks. Such statutes have often included requirements with respect to movement relative to a single floor (“lateral drift”), but more recently have become more focused on interfloor movement (“story drift”). In this regard, California Code has recently been amended to take into account potential story drift events, and specifically, the use of intermediate supports in connection therewith (see California Code Sec. 3137 (d)(2)(C)—“Seismic restraint shall be provided in the transverse direction at all supports. Intermediate supports, if any, shall be free to move laterally in all directions.”).
In order to address such circumstances, there have been a multitude of prior art escalator and/or moving walk designs that have been designed to accommodate aspects of story drift that may occurs during seismic events. For example, U.S. Pat. No. 6,129,198 to Nusime discloses an escalator assembly having a bed support which is in turn supported upon a bed formed as part of the building construction by a resilient mounting element which provides damping for vibration and the like passing between the escalator and the building construction. A second end of the carrier is similarly provided with a bed support which is supported upon a fulcrum firmly mounted to the bed. The fulcrum may be in the form of a screw upon which the bed support is detented and damping means may be incorporated into the fulcrum construction.
Conversely, U.S. Pat. No. 6,637,580 to Sneed discloses a telescoping assembly for an escalator mount that allows movement of the escalator relative to the portions of the building in which it is mounted in a longitudinal direction. Further, the center portion of the mount includes a sill plate that is mounted on a pivot to allow for story drift-type movement.
While all of the foregoing disclosed, and other, prior art structures may have utility in addressing issues with story drift in escalators and moving walks during seismic events, it is still desired to have an escalator or moving walk support structure that provides adequate desired intermediate support for the escalator or moving walk, is relatively simple in design and cost effective in implementation, and which effectively accommodates “story drift” movement that may occur during earthquakes or other seismic events.